Deep Red (1975)

During a special conference on the paranormal, a renowned psychic gets a strange message that a killer is in the audience, and is rushed back to her apartment where she is brutally killed by an unknown assailant. A witness, turns out to be a pianist, teams up with a local reporter to investigate the psychic's death. After interviewing her business partner, they hit a small snag and go their separate ways. After both have hit dead ends with their respective investigations, they put aside their differences and decide to try to solve it together. Following a loose assortment of clues that seem to have no connection to each other, they discover that the killer has been targeting him. As they continue to investigate, a friend makes an important contribution: Armed with this new clue, they start putting the clues together and race to stop the killer before he strikes again.